The invention relates to making interconnections between electronic components, especially microelectronic components and, more particularly, to interconnection elements (contact structures) exhibiting resiliency (springiness), and methods of making same.
Commonly-owned U.S. patent application Ser. No. 08/152,812 filed Nov. 16, 1993 (now U.S. Pat. No. 4,576,211, issued Dec. 19, 1995), and its counterpart commonly-owned copending xe2x80x9cdivisionalxe2x80x9d U.S. patent applications Ser. No. 08/457,479 filed Jun. 01, 1995 (status: pending) and Ser. No. 08/570,230 filed Dec. 11, 1995 (status: pending), all by KHANDROS, disclose methods for making resilient interconnection elements for microelectronics applications involving mounting an end of a flexible elongate core element (e.g., wire xe2x80x9cstemxe2x80x9d or xe2x80x9cskeletonxe2x80x9d) to a terminal on an electronic component, coating the flexible core element and adjacent surface of the terminal with a xe2x80x9cshellxe2x80x9d of one or more materials having a predetermined combination of thickness, yield strength and elastic modulus to ensure predetermined force-to-deflection characteristics of the resulting spring contacts. Exemplary materials for the core element include gold. Exemplary materials for the coating include nickel and its alloys. The resulting spring contact element is suitably used to effect pressure, or demountable, connections between two or more electronic components, including semiconductor devices.
Commonly-owned, copending U.S. patent application Ser. No. 08/340,144 filed Nov. 15, 1994 and its corresponding PCT Patent Application No. PCT/US94/13,373 filed Nov. 16, 1994, (WO95/14314, published May 26, 1995), both by KHANDROS and MATHIEU, disclose a number of applications for the aforementioned spring contact elements, and also discloses techniques for fabricating contact pads (contact tip structures) at the ends of the spring contact elements.
Commonly-owned, copending U.S. patent application Ser. No. 08/452,255 filed May 26, 1995 and its corresponding PCT Patent Application No. PCT/US95/14,909 filed Nov. 13, 1995 (WO96/17278, published Jun. 06, 1996), both by ELDRIDGE, GRUBE, KHANDROS and MATHIEU, disclose additional techniques and metallurgies for fabricating spring contact elements as composite interconnection structures and for fabricating and mounting contact tip structures to the free ends (tips) of the composite interconnection elements.
Commonly-owned, copending U.S. patent application Ser. No. 08/558,332 filed Nov. 15, 1995 by ELDRIDGE, GRUBE, KHANDROS and MATHIEU, and its corresponding PCT Patent Application No. US95/14,885 filed Nov. 15, 1995 by ELDRIDGE, GRUBE, KHANDROS and MATHIEU disclose methods of fabricating resilient contact structures which are particularly well-suited to fabricating spring contact elements directly on semiconductor devices. As used herein, a semiconductor device having spring contact elements mounted thereto is termed a xe2x80x9cspringed semiconductor devicexe2x80x9d.
Commonly-owned, copending U.S. Provisional Patent Application No. 60/024,555 filed Aug. 26, 1996, by ELDRIDGE, KHANDROS and MATHIEU, and PCT Patent Application No. US97/08,606 filed May 15, 1997 by DOZIER, ELDRIDGE, KHANDROS, MATHIEU and TAYLOR disclose additional contact tip structure metallurgies and structures.
The present invention addresses and is particularly well-suited to making interconnections to modern microelectronic devices having their terminals (bond pads) disposed at a fine-pitch. As used herein, the term xe2x80x9cfine-pitchxe2x80x9d refers to microelectronic devices that have their terminals disposed at a spacing of less than 5 mils, such as 2.5 mils or 65 xcexcm. As will be evident from the description that follows, this is preferably achieved by taking advantage of the close tolerances that readily can he realized by using lithographic rather than mechanical techniques to fabricate the contact elements.
As mentioned above, a semiconductor device having spring contact elements mounted thereto is termed a xe2x80x9cspringed semiconductor devicexe2x80x9d. Such a device may be interconnected to an interconnection substrate in one of two main ways. It may be xe2x80x9cpermanentlyxe2x80x9d connected such as by soldering the free ends of the spring contact elements to corresponding terminals on an interconnection substrate such as a printed circuit board. Alternatively it may be xe2x80x9ctemporarilyxe2x80x9d connected to the terminals simply by urging the springed semiconductor device against the interconnection substrate so that a pressure connection is made between the free ends of the spring contact elements and the terminals. Another way of looking at such temporary pressure connections is that the springed semiconductor device is xe2x80x9cself-socketingxe2x80x9d.
The ability to remove a springed semiconductor device from its temporary pressure connection with an interconnection substrate is certainly useful in the context of replacing or upgrading the springed semiconductor device. In this context, it is important that the pressure connections be robust, and capable of withstanding the wear and tear associated with normal operations. Generally, a certain minimum contact force is desired to effect reliable pressure contact to electronic components (e.g., to terminals on electronic components). For example, a contact (load) force of approximately 15 grams (including as little as 2 grams or less and as much as 150 grams or more, per contact) may be desired to ensure that a reliable electrical connection is made to a terminal of an electronic component which may be contaminated with films on its surface, or which has corrosion or oxidation products on its surface. The minimum contact force required of each spring contact element demands either that the yield strength of the spring material or that the size of the spring element are increased. As a general proposition, the higher the yield strength of a material, the more difficult it will be to work with (e.g., punch, bend, etc.). And the desire to make springs smaller essentially rules out making them larger in cross-section.
A more fundamental object is achieved simply by making transient (very temporary) connections to a springed semiconductor device. And that is, the ability to test the springed semiconductor device prior to temporarily or permanently mounting it to an interconnection substrate of a system to (1), if necessary, burn-in the springed semiconductor device and (2) to ascertain whether the springed semiconductor device is measuring up to its specifications. As a general proposition, this can be accomplished by making xe2x80x9ctransientxe2x80x9d pressure connections with the spring contact elements with relaxed constraints on contact force and the like. The making of such transient connections to springed semiconductor devices is the focus of the present invention. The present invention discloses a number of techniques for socketing (making transient pressure connections) to springed semiconductor devices.
According to the invention, methods and apparatuses for effecting a temporary connection to a portion of an elongate spring contact element mounted to and extending from an electronic component are provided.
In one embodiment, an interconnection substrate has a terminal which is a plated through hole. The spring contact element is inserted through the through hole so that a portion of the spring contact element is within the through hole.
Additional methods, apparatuses and embodiments thereof are disclosed herein.
Other objects, features and advantages of the invention will become apparent in light of the following description thereof.